mwifiex: wake up main thread to handle Tx traffic if scan is delayed/aborted

mwifiex: wake up main thread to handle Tx traffic if scan is delayed/aborted

This is a flaw in recently implemented logic to handle Tx traffic
and scan operation simultaneously. We missed to wakeup main thread
to handle Tx traffic if scan is delayed/aborted.

For some cards (SD8797, for example), firmware will send SLEEP event
if there is no activity for 50msec. While handling the SLEEP event,
main thread will be woken up and Tx packet gets sent hence. In worst
case Tx traffic will be delayed for 50msec.

For other cards, such as USB8797, firmware won't send SLEEP event.
So, Tx traffic gets stuck if no other event triggers the wakeup of
main thread.

This patch fixes above issues.

Signed-off-by: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Bing Zhao <bzhao@marvell.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>